1. Field of the Invention
The present invention generally relates to a method of manufacturing a liquid delivery apparatus, and particularly to a method of manufacturing a liquid delivery apparatus using a piezoelectric ceramic material.
2. Discussion of Related Art
There is known as a kind of liquid delivery apparatus used as an ink jet head, an apparatus using a piezoelectric element for pressurizing an ink to eject a droplet of the ink from a nozzle, which apparatus is advantageous, for instance, in that: it is possible to eject a liquid which is not of water type; it is possible to accurately control volume of the droplet of the ink as ejected, thereby enabling to control an area covered by a droplet of the ink in gradation sequence; and the ink jet head exhibits a high durability. JP-A-9-314836 or its corresponding U.S. Pat. No. 5,963,234 discloses such a kind of apparatus used as an ink jet head, comprising: a plurality of pressure chambers each accommodating an ink; and an actuator plate comprising a plurality of piezoelectric ceramic sheets and a diaphragm on which are bonded the piezoelectric ceramic sheets at respective positions corresponding to the pressure chambers, the actuator plate being disposed such that the actuator plate closes the plurality of pressure chambers. Upon application of an electric field on one of piezoelectric ceramic sheets as desired, the actuator plate is locally deflected at the position corresponding to the actuated piezoelectric ceramic sheet, thereby pressurizing the ink in the relevant pressure chamber and ejecting the ink from an opening communicated with the pressure chamber.
To manufacture such a liquid delivery apparatus, there is involved a step of bonding multiple piezoelectric ceramic sheets to a fluid passage unit where multiple pressure chambers and openings each communicating with one of the pressure chambers are formed. The piezoelectric ceramic sheets are obtained by first firing a green sheet of a ceramic material into a large piezoelectric ceramic sheet and then segmenting the piezoelectric ceramic sheet into a plurality of segments by using a diamond cutter or the like.
However, the step of segmenting the piezoelectric ceramic sheet with the diamond cutter or the like inevitably includes a substep which is cumbersome and takes a relatively long time to implement, for instance, spraying a coolant or lubricant, and cleansing relevant members for eliminating chips generated during the piezoelectric ceramic sheet is segmented. Further, since the piezoelectric ceramic sheet as has been fired has a high mechanical strength, the segmenting step requires a large machine such as the diamond cutter. This leads to lowering the yield of the piezoelectric ceramic sheets, pushing up the manufacturing cost of the liquid delivery apparatus. In addition, according to the above-described conventional method, it is essential to position with high accuracy the multiple piezoelectric ceramic sheets on the diaphragm with respect to the multiple pressure chambers.